Laser machining systems and methods are commonly used to machine various types of materials and structures. Such laser machining systems and methods may provide a number of advantages including lower manufacturing costs, increased throughput and production yield, and improved quality. In the area of solar panels, for example, the advantages of laser machining could significantly enhance the efficiency and viability of solar energy technology.
In the manufacture of thin film photovoltaic (PV) solar panels, laser machining techniques may be used to scribe the various thin film layers in a panel to form electrically connected cells. In one type of PV solar panel, three layers are deposited to form the panel and lines are scribed after each new deposition. The area on the panel including these lines is considered a wasted area that does not contribute to solar energy conversion. Thus, the lines should be straight and aligned accurately to minimize this wasted area and to provide the best efficiency. High scribing speeds are also desirable to improve throughput. Providing accurate high speed scribing of thin film PV solar panels (and other similar structures) presents a number of unique challenges.
In particular, the laser machining of scribe lines presents environmental challenges. The laser ablation of certain materials used in these solar panels may generate harmful gases. For example, cadmium telluride (CdTe) is often used as an active conductive layer in thin film PV solar panels, and the ablation of CdTe produces toxic gases. Existing laser machining systems may not effectively handle these harmful gases in a safe and energy efficient manner. Debris removal may be difficult when a moving optical head is used for laser machining and particularly when the debris is generated on the same side of the workpiece as the laser machining and moving optical head.